Testing Methodology

Although the testing of a cooler appears to be a simple task, that could not be much further from the truth. Proper thermal testing cannot be performed with a cooler mounted on a single chip, for multiple reasons. Some of these reasons include the instability of the thermal load and the inability to fully control and or monitor it, as well as the inaccuracy of the chip-integrated sensors. It is also impossible to compare results taken on different chips, let alone entirely different systems, which is a great problem when testing computer coolers, as the hardware changes every several months. Finally, testing a cooler on a typical system prevents the tester from assessing the most vital characteristic of a cooler, its absolute thermal resistance.

The absolute thermal resistance defines the absolute performance of a heatsink by indicating the temperature rise per unit of power, in our case in degrees Celsius per Watt (°C/W). In layman's terms, if the thermal resistance of a heatsink is known, the user can assess the highest possible temperature rise of a chip over ambient by simply multiplying the maximum thermal design power (TDP) rating of the chip with it. Extracting the absolute thermal resistance of a cooler however is no simple task, as the load has to be perfectly even, steady and variable, as the thermal resistance also varies depending on the magnitude of the thermal load. Therefore, even if it would be possible to assess the thermal resistance of a cooler while it is mounted on a working chip, it would not suffice, as a large change of the thermal load can yield much different results.

Appropriate thermal testing requires the creation of a proper testing station and the use of laboratory-grade equipment. Therefore, we created a thermal testing platform with a fully controllable thermal energy source that may be used to test any kind of cooler, regardless of its design and or compatibility. The thermal cartridge inside the core of our testing station can have its power adjusted between 60 W and 340 W, in 2 W increments (and it never throttles). Furthermore, monitoring and logging of the testing process via software minimizes the possibility of human errors during testing. A multifunction data acquisition module (DAQ) is responsible for the automatic or the manual control of the testing equipment, the acquisition of the ambient and the in-core temperatures via PT100 sensors, the logging of the test results and the mathematical extraction of performance figures.

Finally, as noise measurements are a bit tricky, their measurement is being performed manually. Fans can have significant variations in speed from their rated values, thus their actual speed during the thermal testing is being recorded via a laser tachometer. The fans (and pumps, when applicable) are being powered via an adjustable, fanless desktop DC power supply and noise measurements are being taken 1 meter away from the cooler, in a straight line ahead from its fan engine. At this point we should also note that the Decibel scale is logarithmic, which means that roughly every 3 dB(A) the sound pressure doubles. Therefore, the difference of sound pressure between 30 dB(A) and 60 dB(A) is not "twice as much" but nearly a thousand times greater. The table below should help you cross-reference our test results with real-life situations.

The noise floor of our recording equipment is 30.2-30.4 dB(A), which represents a medium-sized room without any active noise sources. All of our acoustic testing takes place during night hours, minimizing the possibility of external disruptions.

<35dB(A) Virtually inaudible
35-38dB(A) Very quiet (whisper-slight humming)
38-40dB(A) Quiet (relatively comfortable - humming)
40-44dB(A) Normal (humming noise, above comfortable for a large % of users)
44-47dB(A)* Loud* (strong aerodynamic noise)
47-50dB(A) Very loud (strong whining noise)
50-54dB(A) Extremely loud (painfully distracting for the vast majority of users)
>54dB(A) Intolerable for home/office use, special applications only.

*noise levels above this are not suggested for daily use

Introduction & the Cooler Testing Results
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  • Avalon - Thursday, October 13, 2022 - link

    Seems like a good cooler and quite similar to the Be Quiet! Dark Rock Pro 4. Any chance you'll be reviewing the latter?
  • ballsystemlord - Thursday, October 13, 2022 - link

    That tower cooler is amazing at higher heat outputs. Perfect for the new AMD/Intel CPUs.
  • rickeo - Sunday, October 16, 2022 - link

    That direct heatpipe contact will likely NOT be good for modern AMD chiplet CPU's.
  • Threska - Thursday, October 13, 2022 - link

    Should have covered ease of installation. Some can be difficult especially dealing with weight and size in an already installed motherboard.
  • meacupla - Thursday, October 13, 2022 - link

    I'm surprised direct touch heatpipes are still a thing. I would have expected the manufacturers to have added a vapor chamber by now. The heat output on these newer chips aren't evenly spread out, unlike when the NH-D15 was released.
  • DanNeely - Thursday, October 13, 2022 - link

    As long as reviewers are sufficiently scared of random temporal variations that they use isothermal resistive heating elements lazy manufactures don't need to bother with actual CPU thermal distributions in the pursuit of fake internet points in review scores.

    Meanwhile manufacuers that do try to take such factors into consideration (a decade ago there was a CPU waterblock manufacturer that offered different flow guides for different CPU families for an extra 1-2C cooling vs a generic setup) at best get no benefit for their work and at worst actually score worse because they're not as efficient at cooling a space heater where actual CPUs don't put much of their heat.
  • thestryker - Thursday, October 13, 2022 - link

    While I agree with you in principal you're also asking reviewers to do a *lot* more work and have results which can't be directly compared. Intel's CPUs, at least until MTL, the heat is right in the center whereas AMD has been off to the side which means you'd have to test both if you want useful results. On top of that you'd also have to test with an offset (or whatever other method is being used) and without to see if there is an actual benefit (Der8auer tested AMD offset on Zen 4 and found no difference).

    In the end so long as reviewers address the availability of any extra features which may assist specific platform cooling that's good enough for me.
  • 404NotFound22 - Friday, October 14, 2022 - link

    Actually no, while Der8auer himself didn't find a difference, his comment section sure did. The benchmark score went up, while the temperature remained the same, as is expected from Zen 4. He admitted not seeing this and said a revised video is coming.

    So yes it did make a difference.
  • thestryker - Friday, October 14, 2022 - link

    He's running a manual OC on the chip, so no that behavior is not expected at all. We won't know what's going on until he's able to rerun the testing.

    (I'd missed the benchmark performance entirely though since I was only listening to the video)
  • Stuka87 - Thursday, October 13, 2022 - link

    There have been vapor chamber coolers in the past, such as the CoolerMaster TPC 812. With the way current CPUs have very uneven hot spots, vapor chambers do start to make more sense.

    The IceGiant ProSiphon is the closest thing we have these days, and it does work really well, though its on the large side.

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